You are here

Leather processing

In an age of plastics, metals and synthetics, leather has kept its place as a product of superior quality. As a result, tanning remains an essential economic activity. Leather processing can be done at the small-scale or large-scale level, all to varying degrees of sophistication.

The tanning industry has been subject to important challenges and changes. Foremost has been the introduction of processing technologies with less impact on the environment. As the production of finished leather is concentrated in developing countries, UNIDO, together with other partners, have provided support to enhance tanning industry practices in developing countries.

Cleaner leather production technologies remain UNIDO’s main focus in the field of leather processing. Cleaner production applications include green hide and skin processing (supply of raw material from slaughterhouses without preservation, e.g. salting), water management (use minimum volume of process water), recycling (e.g. in liming) and chromium recovery (after tanning), hair saving (to reduce dissolved solids in effluent) and application of environmentally friendly chemicals (e.g. enzymes). Special attention is also given to occupational health and safety (OHS) in tanneries.

The study titled Life Cycle Assessment, Carbon Footprint in Leather Processing prepared for and presented by F. Brugnoli during the XVIII Session of UNIDO Leather and Leather Products Industry Panel in Shanghai in 2012 provided detailed explanations, definitions and terminology pertaining to leather’s carbon footprint.

It also contained specific suggestions on how to proceed in addressing this issue. Subsequently, it was not only extensively discussed by eminent international leather specialists, but it has triggered a series of activities involving different regional and global establishments.

The essence of that paper, reactions to it and some other views were reflected in a special chapter in UNIDO’s comprehensive study The Framework for Sustainable Leather Manufacture, a chapter dealing with carbon footprint aspects of leather processing.

That chapter is now here presented as separate paper for the benefit of readers primarily interested in the carbon footprint considerations.

In addition to earlier content, the paper also presents the main features of the European Standard EN 16887 (approved in Nov 2016, published in March 2017, applicable not later than Sept 2017) Leather – Environmental footprint – Product Category Rules (PCR) – Carbon footprints. It is quite likely that the European norm will prevail globally.

Historically, for various reasons, tanneries have been generally found in clusters in many countries. In several countries that still possess a strong tanning industry, the industry has either been able to deal collectively with the environmental challenges by means of common waste treatment facilities in existing clusters (e.g. India, Italy, Pakistan) or is in the process of relocation.

Within almost all projects of tannery relocation there are common reasons and the main problems faced by the industry at the current location are:

With no infrastructure for treatment of solid or liquid waste generated by tanneries, a very unhygienic atmosphere has been created in the entire locality due to discharge/disposal of untreated solid and liquid wastes.

Due to extreme limitations of space, even tanneries wanting to modernize and become more efficient in terms of production and environment management are unable to do so. The present location, in this manner, has become a serious constraint for the growth of the industry.

Downstream industries such as footwear, leather garment and leather goods, depend on the tanning industry for supply of quality leather. The existing limitations have put a limit to the growth of leather products industries.

Relocation of the tanneries to a more spacious location with appropriate infrastructure for efficient and cost effective treatment of solid and liquid wastes has thus become a prerequisite for survival and growth of the leather industry in such cases.

The precarious situation with water and soil pollution in the area of tannery clusters along the Palar River prompted the state environmental authorities to press for adherence to TDS discharge limits as well as to impose an approach not practiced in the tanning industry: a Zero Liquid Discharge (ZLD) concept.

Essentially, the ZLD systems concentrate dissolved solids by Reverse Osmosis (RO) and some kind of Multi Effect Evaporation (MEE) until only damp solid waste remains. Solid waste is disposed and nearly all water is reclaimed and reused. Accordingly, some of the existing Common Effluent Treatment Plants (CETPs) have been supplemented by RO and MEE, together with auxiliary steps (tertiary treatment, water softening etc.).

The analysis investigates and relates raw and equalized effluent inflows, RO feed, permeate and reject, evaporator feed and condensate and the yield of recovered, reusable water. Since the energy costs are critical for the viability of the entire concept, data about energy consumption (thermal, electrical main and Diesel) at key stages (RO, multistage evaporation) are consolidated, analysed and correlated. Additional energy needs and costs are compared with those for conventional (CETP) treatment and estimates made of the carbon footprint increase caused by the ZLD operations.

Confronted with increasing legal and social pressures, no tanner can afford the luxury of not being familiar with the main issues and principles of occupational, safety and health protection pertaining to tannery operations.

Hydrogen sulphide gas present in tanneries and effluent treatment plants has proven fatal to workers exposed to it many times.

It is therefore necessary that the owners and managers of tanneries and effluent treatment plants are fully aware of the dangers posed by this poisonous gas and take all preventive and precautionary measures to protect the workforce from exposure to this gas. In the event of accidental exposure of a worker, they should know how to deal with the situation.

The lessons that follow are to help tanners, tannery managers and operators to acquaint themselves with the basic principles How to deal with hydrogen sulphide gas.

The on-line course developed by UNIDO including test provides an opportunity for the proper training within tanneries related to danger associated with hydrogen sulphide gas. After finishing the test with minimum score 80%, participants will receive the certificate and will be able to download it.

How to enrol into the UNIDO on-line course “ How to deal with hydrogen sulphide gas”?

Hydrogen supplied gas present in tanneries and effluent treatment plants (ETPs) has proven fatal to workers exposed to it many times.

It is therefore necessary that the owners and managers of tanneries and effluent treatment plants are fully aware of the dangers posed by this poisonous gas and take all preventive and precautionary measures to protect the workforce from exposure to this gas. In the event of accidental exposure of a worker, they should know how to deal with the situation.

UNIDO’s activities in the leather processing has as one of its important objectives, improvement of occupational safety and health practices in tanneries and effluent treatment plants. Under this objective, the project has been seeking to demonstrate in selected tanneries improvement practices for better occupational health and safety of the workers.

It is hoped that the industry representatives and other concerned with the occupational health and safety of workers in tanneries and effluent treatment plants will find this publication useful.

Throughout the world, women make a vital contribution to industrial output.. Their work not only sustains their families, but also makes a major contribution to socio-economic progress. The creativity and talents of all women are an invaluable resource, which can and should be developed both for their own selfrealization and for the benefit of society as a whole.

The key to enhancing women’s opportunities, and hence their position in industry and the economy, is to provide them with access to know-how, technologies and credit. Training to upgrade women’s technological capabilities and to enhance their entrepreneurial and business skills, whether in simple artisanal production or in high technology industries, is at the heart of allowing women to advance to more rewarding positions. All these activities are an integral part of UNIDO’s technical assistance programmes.

The case-studies presented in this series of brochures demonstrate that engament of women women and gender neutral management can be also for benefit of the leather sector.

Tanning industry is an important segment of UNIDO technical assistance in promoting sustainable development. In late 90-ies a number of studies dealing with various cleaner tanning methods, including the widely used paper The Scope for decreasing pollution load in leather processing, were prepared to support different forms of training activities (shop-floor demonstrations, pilot plants, national and regional workshops etc).

In the meantime a lot of practical experience has been gathered, some new tanning technologies developed and implemented and some new challenges have also emerged. Since proper training is essential precondition for modern, sustainable leather processing, it is felt that a single, comprehensive paper on cleaner leather technologies, rounding up and updating earlier papers, could be of great help in training and capacity building activities.

The study also includes many tables, charts and (equipment) photos accompanying and illustrating the text.

It is envisaged that the document will serve as a basis for developing globally accessible eLearning courses on sustainable leather manufacture.

There are also other useful information and sources e.g. Tannery of the Future. The Tannery of the Future tool gives tanners an initial indication of the areas in which they need to become more sustainable, e.g. housekeeping, waste management, working conditions and wages. It also provides references to sources of more in-depth information and guidance.

Machines and mechanical equipment play an important role in modern tanneries. Though these results in increased productivity, their use has also introduced new hazards into the tanneries.

One element of OHS, which is contained in the knowledge and expertise of the workforce, is the skill of re blading.

Malpractice and lack of knowledge in this area, have initiated the manufacturing of the manual presented in this report. This report is prepared as a manual for re blading of cylinders, for the use in ttanning industry.

The paper presents the results of the implementation of solar collectors in three Bangladeshi tanneries as well as of energy audit in four Bangladeshi tanneries to evaluate and improve their electrical performance.

It is well known that tanneries use high amounts of hot water and electricity, and today energy costs are raising very fast all over the world, with energy costs increasing their share in the costs of leather production. Other problem especially in developing countries are frequent power cuts and problems with energy supply. Tannery relocation planned in Bangladesh from Hazaribagh to new Tannery Estate Dhaka is an opportunity to implement measures to reduce energy consumption which should lead to reduced costs for production but also reduced GHG production. Therefore, within the Re-Tie-Bangladesh project (Reduction of Environmental Threats and Increase of Exportability of Bangladeshi Leather Products1) UNIDO has implemented two actions to reduce energy costs in Bangladeshi tanneries: use of solar energy - solar water heating and electrical performance improvement.

The Global Leather Coordinating Committee (GLCC) in 2013 sought to identify real and perceived strengths, weaknesses, opportunities and threats of importance to the leather industry. This paper sets down a mosaic of major issues stemming from these considerations.This paper was published in the World Leather (February/March 2014).